The invention relates to hook and loop fasteners and their method of manufacture.
Hook and loop fasteners comprise mating strips or patches of filamentary stress-bearing hooks and loops. The hooks are woven, and the loops are knit or woven, into a textile backing, or ground. In order to secure the hook or loop elements to the ground, and to bond the fibers composing the ground to each other, in a manner to withstand the forces involved, the ground is impregnated with a resinous binder to form a composite structure.
The binder matrix adds strength and durability to the fastener. Depending upon the quality of the binder, the hooks and loops may pull out of the ground, and the ground may start to fray, after a number of cycles of closing and opening the fastener. Thus, the binder is an important element in the system.
The material used for the binder greatly affects the fastener's performance. It is desirable that the material be able to withstand numerous cycles of opening and closing, and not break down appreciably under laundering or dry cleaning conditions.
In addition to the particular material used for the binder, the manner in which the binder is applied can affect the fastener's performance. For optimal strength, the binder should impregnate the ground as fully as possible. At the same time, it should not be allowed to wick into the hooks or loops, as that interferes with their ability to engage each other and reduces the effectiveness of the fastener.
The manner in which a binder is applied also affects the cost to produce the fastener. Current fasteners often use binders which are applied to the ground as a solution or as a dispersion. These binders require additional chemicals to effect their cure (cross-linking), and ovens to dry them and promote their cure; the production line can be quite long as a result. The chemicals used to cure the binder, e.g., formaldehyde or aziridines, are often environmentally undesirable, if not toxic. Thus, high energy and capital costs, extensive factory manpower and floorspace, and environmental undesirability are often associated with the binders currently used in hook and loop fastener systems.
An object of the present invention is to provide hook and loop fasteners with improved qualities related to binder performance and another object is to provide improved methods and systems for manufacturing hook and loop fasteners in respect of the binders employed.